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| Effects of Low-Molecular-Weight Organic Acids on Adsorption of Quinclorac by Hematite |
| Received:January 21, 2015 |
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| KeyWord:low-molecular-weight organic acids;hematite;quinclorac;adsorption;mechanism |
| Author Name | Affiliation | E-mail | | YANG Li-hua | College of Resource and Environment, Hunan Agricultural University, Changsha 410128, China
Institute of Agricultural Environmental Protection, Hunan Agricultural University, Changsha 410128, China | | | GONG Dao-xin | College of Resource and Environment, Hunan Agricultural University, Changsha 410128, China
Institute of Agricultural Environmental Protection, Hunan Agricultural University, Changsha 410128, China | gdx4910@163.com | | YUAN Ya-jie | College of Resource and Environment, Hunan Agricultural University, Changsha 410128, China | | | ZHOU Jian | College of Resource and Environment, Hunan Agricultural University, Changsha 410128, China | | | XIAO hao | College of Resource and Environment, Hunan Agricultural University, Changsha 410128, China | |
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| Abstract: |
| Adsorption of chemicals in soil greatly influences their bioavailability and environmental fates. Here the effects of six low-molecular-weight organic acids on the adsorption of quinclorac by hematite were studied using batch equilibrium technique. The adsorption mechanisms were also explored by FTIR spectral analysis method. Freundlich equation fitted well the adsorption isotherms of quinclorac on hematite under the presence of six low-molecular-weight organic acids at different concentrations(R2 >0.749). Total sorption capacity(lgKf)of quinclorac on hematite was in order of acetic acid>oxalic acid> succinic acid> tartaric acid >malic acid >citric acid. All six organic acids mildly promoted the adsorption of quinclorac on hematite at the concentrations of 0 to 32 mmol·L-1, with the strongest promoting effects by oxalic acid at high concentrations. Results of FTIR showed that the adsorption of quinclorac by hematite was mostly via weak forces such as H-bond, complexation reaction, charge transfer and so on. The typical peaks of the Fe-O bond in a-Fe2O3 did not change before and after adsorption, suggesting that the adsorption occurred on the surface of hematite.The binding of organic acids with Fe-O bonds facilitated the formation of Fe-O-quinclorac-acetic acids structure on the surface of hematite. |
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